Temp and fuel gauges

Hiya Guys/girls
I've got a 83 gti tin top with a ABF engine conversion but having issues with the temp and fuel gauges, 
They suddenly stopped working, they did once briefly start to work but then died again as soon as they started to work !!
Any ideas?
Cheers in advance 
Gary

Sounds like a bad earth or bad connection somewhere to me.

Probably wrong though……

Welcome along btw

Ian

Thanks for the welcome Ian 👍
Any ideas as a starting block?

If both gauges aren't working then you have a issue with the 10V stabiliser on the back of hte cluster.

It is a lm7810  ka7810-aet.  They are about a pound or less at a electronics store.

You can test it.

open the car to get to the cluster.
On the back is a 3 legged solid state thing.
The middle leg is ground.
Key in and in the run postion,  The other 2 legs will be 12V (battery), and the other 10V.

It could also be flaky connections on the cluster pins, that is 14, and 2 14 black is Battery Positive, pin 2 brown is earth.

Wow !!
What a great and detailed answer, thank you very much for your reply… will get on it and report back to you.
Thanks once again.
Gary

Briano1234 said

If both gauges aren't working then you have a issue with the 10V stabiliser on the back of hte cluster.

It is a lm7810  ka7810-aet.  They are about a pound or less at a electronics store.

You can test it.

open the car to get to the cluster.
On the back is a 3 legged solid state thing.
The middle leg is ground.
Key in and in the run postion,  The other 2 legs will be 12V (battery), and the other 10V.

It could also be flaky connections on the cluster pins, that is 14, and 2 14 black is Battery Positive, pin 2 brown is earth.

Exactly what I was going to say………………  

 

Thanks Briano1234  knew you'd be along to say 'howdy'  

Ian

Well I've changed the 3 prong pin thing and still not working! Arghhh
Also they started to smoke as two of the track wire came together, not looking good 😢

Did you look at the spec diagram for the new part, some of the new ones have the pins reversed, and it won't work right unless you flip it over.

"two of the track wires"?  Are you talking about the mylar circuit traces….?   

The Gauges started to smoke?

If the stabilizer was incorrect or installed wrong, it is possible that the gauges would over heat…. it isn't that they may be bad, but inside of the 2 gauges is a nica-chrome wire wrapped around a Bimetalic spring.  

It is basically a toaster… heat up move the needle.
They are more prone to cold solder joints, I have never seen one smoke.

To be honest I just went into maplins, they googled the part and gave me the new 3 prong thing. Fitted it then
I cleaned up the copper trace connections, put it back together and still no temp/ fuel gauge working.
The smoke came from another part of the clocks where the blue plastic which contains the copper wires, came in contact with another part of the blue plastic, which caused the smoke
I have got a picture of this part but not sure how to upload.
Gary

Post the pictures in to the thread, so others can view them.



Which specific Traces on the mylar burnt, I see a couple that may be them.  The issue is that as our car ages the mylar is taking the worst for it as it is becoming Brittle and delaminating….so you have to be very careful of bending it and things.

Be very careful with what you clean it with, for the copper pads a q-tip or cotton swap moist with alcohol is best.
An eraser (pencil) will shine them, but may also lift the traces.  Great Care must be taken.

 

Is the black tape supposed to hold down the two parts and it's just that the tape has lost its sticky?

Yes.

Oh ok
This was the part that I thought had come in contact with one another hence the smoke
But seems it may  have come from elsewhere 

Usually the Instrument lights or headlight switch releasing all the smoke from the gray/blue wire… If you have the cluster connected, then the 3 legged thing should have battery to center pin on one side, and 9-10V to center on the other.  If you don't then you have issues with either the Ground wire to component, or Power in to it.  (that is the Black wire on the connector of the cluster 12V battery) and Brown wire which is ground.

Take the nuts off the gauges and clean them with sandy paper to get them bright and shiney.  Take Steel Wool and use it to clean the screw posts…and to slightly brighten the mylar pads.  Reconnect the nuts and tighten not overly tight snug……

inside of the fuel gauge where the wires go to the studs can get cold soldered and stop it from workign or working intermittently.



inside shot of the Fuel and Water gauge….

from your photos:




I would start looking for an instrument cluster.  The Crimp connections on the mylar are all corroded, and need to be resolved.  Trying to splice a new resistor in for the place of the old one isn't a easy task, and I don't know the value of the resistor in question….
 

Cheers for all the help guys, as I thought a replacement cluster is the only way to sort it.
Thanks again Guys 
Gary

All sorted now, turns out it was the 3 prong part, maplins supplied me the wrong parts 
A big thank you to Richard at crazyquiffs for sorting my cluster out.
Gary